As illustrated and described in Koenig, Jr., U.S. Pat. No. 5,313,755, a drywall corner-finishing accessory comprises three integrally joined, elongate strips, namely two relatively rigid, lateral strips and a relatively pliable, middle strip, which may be respectively coextruded from polyvinyl chloride having different durometer hardnesses. Each lateral strip has a rib along one edge. At its opposite edges, the middle strip is joined to the lateral strips at the distal edge of the ribs, so that a broad surface of the middle strip is stepped from the lateral strips.
As illustrated and described therein, the drywall corner-finishing accessory is flexible along the middle strip selectively to define a stepped, inside corner and a stepped, outside corner. The rib of each lateral strip guides a drywall-finishing tool and has a grooved pocket opening toward the distal edge of such lateral strip to receive drywall-finishing material.
Although the drywall-corner finishing accessory illustrated and described therein can be also used as an expansion joint between two drywall panels, it has been found to be a practical necessity either to mask the middle strip, as with masking tape, when drywall-finishing material is applied over the lateral strips or to clean such material from the middle strip after such material has been applied over the lateral strips, before the accessory and the applied material are finished, as by painting or wallpapering. Otherwise, as the drywall panels expand or contract so as to flex the middle strip, any finishing material remaining on the middle strip and painted may have a tendency to crack or to separate from the middle strip so that the expansion joint may need to be then refinished at least along the middle strip.
This invention provides improvements over the drywall corner-finishing accessory illustrated and described in Koenig, Jr., U.S. Pat. No. 5,313,755.